This invention relates to an image forming apparatus for electrophotographic image formation, the apparatus forming a toner image on a photoreceptor surface, primarily transferring the image from the photoreceptor surface to an intermediate transfer member, and secondarily transferring the image from the intermediate transfer member to a sheet.
An image forming apparatus including an intermediate transfer member is, for example, an apparatus as disclosed by Japanese published unexamined application No. 2010-14995, in which a preliminary charger is disposed in the motion direction of the intermediate transfer member, downstream of a primary transfer position and upstream of a secondary transfer position. The preliminary charger applies, after the primary transfer and before starting the secondary transfer, a charge to a Loner image on the intermediate transfer member, the charge having the same polarity as the charge polarity of the toner image. The electrostatic charge state of the toner may thus be stabilized, thereby improving the transfer efficiency during the secondary transfer.
During the image formation, the intermediate transfer member is in pressure contact with the photoreceptor surface to receive the toner image transfer from the photoreceptor surface. After the image formation, the transfer member is spaced apart from the photoreceptor surface to reduce deformation and adhesion. If the intermediate transfer member is spaced apart from the photoreceptor before the secondary transfer end, the distance between the intermediate transfer member and the preliminary charger changes, thereby making it difficult to apply the appropriate potential to the toner image on the intermediate transfer member from the preliminary charger. It is thus difficult to space the intermediate transfer member apart from the photoreceptor before the secondary transfer end, thereby increasing the time of amount before starting the next image forming process.
It is an object of the invention to provide an image forming apparatus that may space the intermediate transfer member apart from the photoreceptor immediately after the primary transfer to reduce the amount of time before the next image forming process.